The steering and stability characteristics of motorcycles, bicycles and other similar types of vehicles can be varied and altered in a number of different ways. For example, altering the front wheel assembly rake and trail angles can change the steering and stability characteristics of a motorcycle. The rake angle is defined as that angle which the steering axis of the front wheel assembly of the motorcycle has relative to an imaginary vertical axis or plane. Thus, if an imaginary vertical plane is passed through the steering head assembly of a motorcycle, the rake angle is that angle formed between such plane and the steering axis of the front wheel assembly. The horizontal distance of the forward wheel's axle from a pre-defined measure is generally referred to as a motorcycle's trail. A motorcycle's trail has been defined as the horizontal distance by which a vertical plane, passing through the front wheel axle trails the point of intersection of the steering axis with a horizontal ground.
Variations in the rake and trail angle of a motorcycle will provide different ride and steering characteristics. For example, in a chopper-type motorcycle, the rake angle may be quite large, such as 35 degrees or more. This design allows motorcycles to be very stable at high speeds on straight roads and also is very comfortable to ride for long distances. However, chopper-type motorcycles are difficult to steer on winding roads, as they generally require much upper body strength to maneuver the motorcycle. On the other hand, if the rake angle is considerably smaller, i.e., 28 degrees or less, the motorcycle steering will be quite sensitive and responsive, but the stability of the motorcycle on a fast straight section of road tends to be considerably less than desirable. Also, riding for a considerable distance tends to be uncomfortable, as the rider is positioned in more of an upright position than would be on a chopper-type motorcycle.
Heretofore, motorcycle owners have had to choose between chopper-type motorcycles and “stock” motorcycles (i.e., those motorcycles having a relatively small rake angle). However, certain motorcycle designs have been devised which allow changing of the rake angle depending upon road conditions and motorcycle use. In particular, U.S. Pat. Nos. 3,866,946 and 4,082,307, U.K. Pat. No. 570,439 and Italian Pat. No. 523,424 all disclose various mechanical arrangements which permit the rake angle of the front fork assembly of a motorcycle to be changed. While each of the designs disclosed in these particular patents are specifically different, they all achieve fork angle change basically in the same manner. This manner requires that the motorcycle be stopped, that the operator then disassemble portions of the motorcycle steering head assembly to remove or alter components thereof in order to change the rake angle, and that the operator then reassemble the steering head components with the rake angle at its new position. Should the operator subsequently choose to again change the rake angle due to new road conditions or the like, the same cumbersome and time consuming procedure is required. Thus, while the rake angle of such motorcycle front wheel assembly designs is variable, it certainly cannot be varied conveniently. Moreover, these designs do not permit variance of the fork angle during actual operation of the motorcycle.
Another shortcoming of motorcycles today is that they are typically mass-produced and do not allow a purchaser a customized “fit”. The purchaser is forced to buy the motorcycle “as is” and must then alter it to accommodate his or her body.
Consequently, there is a need for a motorcycle front wheel assembly design wherein the rake angle can be easily changed as desired by the motorcycle operator to permit larger rake angles during straight away motorcycle operation and shorter rake angles during turning and off-road operations.